From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8DCAFC54EBD for ; Mon, 9 Jan 2023 22:18:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673302731; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=tomsOGYF9wYeM5sWYjmtfIxDx+nDca2PZQAJ+amsbhk=; b=ikOmO4EOW+f2KzQhjjf03flWLzcrmXjcjwTeNrSgGZp7nsMgIMvV/nOPIHuM1MHOq54un7 QLRMlO5ZFua9feUeDiII7pHNjJ/IbHSsU56WfMZIsZ045SnP/aWwNokrzeIoo1vB+cBX/N GTLppjkxLgQaygHR7G2KD29wVjr2J4c= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-649-L5cw3-xiNySYLT9AZhS6hw-1; Mon, 09 Jan 2023 17:18:48 -0500 X-MC-Unique: L5cw3-xiNySYLT9AZhS6hw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3DF6829AB3F9; Mon, 9 Jan 2023 22:18:45 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 155972166B26; Mon, 9 Jan 2023 22:18:41 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id C55D51949751; Mon, 9 Jan 2023 22:18:39 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 523671946587 for ; Mon, 9 Jan 2023 22:18:38 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id 1062440C1060; Mon, 9 Jan 2023 22:18:38 +0000 (UTC) Received: from [10.40.195.83] (ovpn-195-83.brq.redhat.com [10.40.195.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7346740C1141; Mon, 9 Jan 2023 22:18:37 +0000 (UTC) Message-ID: <255eaaae-e30b-2e69-cc03-38ca34902d16@redhat.com> Date: Mon, 9 Jan 2023 23:18:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.6.0 To: LVM general discussion and development , Zhiyong Ye References: <930cea69-8e7a-d0df-a48c-93e7a668be2f@redhat.com> <2b1466c2-f545-d06a-6ce4-d420ed038ad1@gmail.com> From: Zdenek Kabelac In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Subject: Re: [linux-lvm] The feasibility of implementing an alternative snapshot approach X-BeenThere: linux-lvm@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: LVM general discussion and development Errors-To: linux-lvm-bounces@redhat.com Sender: "linux-lvm" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Dne 09. 01. 23 v 7:21 Zhiyong Ye napsal(a): > Hi Zdenek, > > Thank you for your detailed answer. > > For the thin snapshot I will use the latest version of kernel and lvm for > further testing. I want to use both snapshot methods (thin and thick) in the > production environment. But if the thick snapshot is only still in the > maintenance phase, then for thick lv I have to see if there is any other way > to accomplish the snapshot function. FYI - there are still some delays with up-streaming of the latest improvement patches - so stay tuned for further speedup gains & IO throughput with thin provisioning) By the maintenance phase for old thick snapshot I mean - the development of the existing thick snapshot target is basically done - the format is very ancient and cannot be changed without major rewrite of the whole snapshot target as such - and that's what we've made with newly introduced thin-provisioning target which addressed many shortcomings of the old dm-snapshot target. > I use lvm mainly for virtualized environments. Each lv acts as a block device > of the virtual machine. So I also consider using qemu's own snapshot feature. > When qemu creates a snapshot, the original image used by the virtual machine > becomes read-only, and all write changes are stored in the new snapshot. But > currently qemu's snapshots only support files, not block devices. Depending on the use-case it might matter to pick the best fitting chunk-size. i.e. if the changes are 'localized' in the filesystem areas to match thin-pool chunks (also selection of the filesystem itself might be part of equation here) - even if you use snapshots a lot, you may eventually get better result with bigger chunks like 128k or even 256k size instead of default 64K. Regards Zdenek _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/